Primary headteachers and deputes have backed a motion calling for councils to be more "honest" about what schools can achieve in "the current climate of savings and cutbacks".
Ann McIntosh, head of Balfron Primary in Stirling, said local authorities were sending out the message that schools could "do more with less"; that was "not honest".
Ms McIntosh also wanted greater honesty about the impact of the Additional Support for Learning Act, which she said was driving school agendas, eating up time and affecting the ability of heads to "take forward the big picture".
Last year, AHDS backed a motion calling for the Scottish Government to "explore and address" the challenges faced by schools in meeting the needs of pupils with social and emotional difficulties while developing curricular and learning initiatives.
AHDS wants a maximum class size of 30 at all stages, but with a teacher- pupil ratio of 1:24 (an individual pupil with additional support needs should be counted as four for the purposes of the ratio); headteachers should then have the flexibility to distribute teachers across the school as he or she sees fit.